The present invention concerns wireless technologies for electronic devices within a single interior location. This category of wireless technology is often referred to as "local" wireless communication.
There are a number of products utilizing infrared signals for local wireless communication in the computer and electronics industry. Infrared's advantages over other wireless technologies include low cost, low complexity, low power consumption, and directionality. Because the infrared signal is generally directional, it provides high security and low interference with other local signals. However, signal directionality is also infrared's primary limitation; devices must typically be in line-of-sight, that is the infrared transceivers must be generally pointed at each other in order to maintain connection. Another limitation is that infrared signals will not pass through solid objects. Therefore, the signal path must also be clear of obstacles.
In contrast to infrared, radio and cellular waves can pass through solid objects and need not be directed in local areas. However, radio and cellular systems typically require more power than infrared, are bulkier, more costly, and require an antenna for clear reception. Further, they are less applicable to environments where several other wireless devices are in operation, because the likelihood of interference and possible signal tampering is increased. An example of such interference is often found in the cordless phone.
An important factor in the use of wireless communication systems is the intended environment. Infrared links are often favored in large office environments because they may be locally directed, and may therefore be arranged such that various infrared signals utilized simultaneously by different workers will not interfere with one another. However, workers are still generally tied to their respective workstations due to infrared's line-of-sight and obstacle-free limitations.
Small businesses are a different case. They often have fewer than ten employees, and in many cases comprise only a sole professional or tradesperson. For these businesses interference issues are less important. Further, there is a wider variety of workspaces and working styles; owners and employees are more likely to work at a coffee table, sofa, easy chair, or other non-traditional workspace. These people often use portable computers and frequently need to reconnect modem, fax, and printer cables when moving around in their workspace or returning from meetings and business trips.
The number of home computer users is growing due to the evolution of the internet and developments in integrated home computer solutions such as Web-TV. The home may represent an even smaller environment and fewer number of users than a small business, and the nature of the computer workspace and user interaction becomes even more varied; computers are used in living rooms, bedrooms, kitchens, home offices, basements, dens, game rooms, and so on. The structure of these computer interaction environments can differ markedly from that of the standard desk workspace found in most offices.
Finally, hotel rooms, conference rooms, and other temporary locations are also becoming common environments for the use of portable computers such as laptops, notebook computers, and palmtops. These areas have environments similar to those of the small business and home.
There is thus a need for an improved yet economical infrared connection for local wireless communication between computers and peripherals. Further, the need is greater in the small business, home, and remote location environments than in the large corporate environment because: a) low cost is generally more critical in the smaller environments than in the corporate environment, b) flexibility of workspace and habits is more varied in the smaller environments than in the corporate environment, c) many corporate environments are already served by wireless LAN systems, which are not appropriate for the smaller environments, d) interference dangers are limited in the smaller environments, and e) extended use of internet, email, and integrated home computer solutions is greater in the smaller environments, thereby requiring improved flexibility in computer location and use. The present invention relates to an apparatus for communicating local electronic data using infrared waves that meets the needs listed above and that may be employed in a number of applications.
U.S. Pat. No. 5,345,327 to Savicki [1994] discloses a system for diffuse infrared communication comprising two particularly distinguishing features:
a) detection of the edge of the digital infrared signal, and
b) use of a non-directional concentrator in the form of a convex hemisphere.
However, the system to Savicki suffers from the following disadvantages:
a) a single system employing edge signal detection is inferior for use among a variety of devices. Because edge signal detection relies on a relatively consistent and known slope of the infrared signal frequency in order to differentiate the signal from the ambient noise frequencies, it cannot be easily employed with devices where the incoming signal is of varying waveform or irregular cycle, such as the case with modems, keyboards, and printers, unless a substantial amount of additional processing electronics are incorporated to identify the signal. This requires additional cost and complexity in the processing circuitry, or requires that the transceiving devices are placed in line-of-sight with each other to reduce the possibility of interference with other signals and ambient noise.
b) the system is not applicable for simultaneous two-way communication between the transceivers, as needed in the case of a modem or printing with handshaking to maintain data integrity. This is because the forms of the outgoing and incoming edge-detected signal are the same, thereby necessitating that each transceiver wait until a message is received before sending a reply in order to avoid interference between signals within the system. Thus, while the Savicki signal may be differentiated from the ambient noise, it suffers from the undesirable possibility of interference within its own system when simultaneous two-way communication is required.
c) a convex non-directional concentrator is less efficient due to loss of light flux in the infrared range than an alternative receiving lens disclosed in the present invention, and does not help to alleviate the need for the transceiving elements to be in line-of-sight.
d) the system is limited to a preset directionality of infrared signals, and cannot be modified by the user for uni-directional use when a direct path of communication is desired to reduce interference.
U.S. Pat. No. 5,359,189 to Savicki [1994], discloses a non-directional concentrator comprising a hemispherical lens having a radius of a specified range and a flattened top. While the disclosed concentrator improves non-directional infrared data communication, the hemispherical shape is less efficient than an alternative receiving lens disclosed in the present invention, and does not in itself alleviate the need for the transceiving elements to be in line-of-sight. Further, the concentrator does not provide for adjusting the system for wider or narrower bands of directionality.